The present embodiments relate to a method for safety-directed wireless signal transmission and to a device for performing the aforesaid method.
The term “signal” is generally understood to refer to an element of information transmitted using electrical, electronic, or electromagnetic devices, such as a control command issued by a command generator to a system controller. This type of signal is described as safety-related when it must be ensured for safety reasons that an error in the transmission of the signal is ruled out or at least detected. A signal should be regarded as safety-related if an error in the signal transmission would result in the risk of damage to objects or injury to persons.
In a medical diagnostic or treatment system, for example, an x-ray system, there are usually a number of safety-related signals to be transmitted. For example, controlling the x-ray emitter of the system and activating the motor drive of a patient table associated with the system represent safety-related signals of this kind. The x-ray emitter or the motor drive of the patient table is controlled in accordance with the control commands initiated by the operating personnel. If the signal transmission fails, in order to prevent injury to the patient being treated and/or the operating personnel, the x-ray emitter or the motor drive should be placed into a safe state without delay.
Generally, a safety-related signal is transmitted by a cabled connection. In order to increase safety, it is customary in this case to transmit the signal redundantly, for example, in parallel over a plurality of independent signal channels. A hybrid transmission structure is also occasionally used. A hybrid transmission structure has a partial signal transmitted in a signal channel in the form of a software telegram, while a further signal channel is a simple physical cable connection. An actual function selection (e.g. raise patient table) is transmitted via the first signal channel, for example, while a general release of the device motor drive (e.g. enable the motor voltage) is effected via the second signal channel.
In order to be able to comply with comparable safety requirements of wireless signal transmission, the transmission structure is traditionally redundant, for example, implemented using two independent infrared transmission links. Wireless signal transmission devices suitable for transmitting safety-related signals usually have a comparatively complex structure.